We have developed a cinevideodensitometric method for measuring the absolute dimensions of coronary stenotic lesions from conventional coronary arteriograms based on a mainframe computer system. We have adapted this system to practical microprocessor instrumentation and validated its accuracy in radiographic phantom experiments. The research proposed in this continuation application is designed to: 1) validate the accuracy of this microprocessor method in studies of acrylic resin casts of coronary arteries prepared in postmortem human hearts; 2) determine the effect of film speed and latitude, catheter radiopacity, and contrast injections on the accuracy of cinevideodensitometric measurements; 3) describe the clinical utility of cinevideodensitometry in planning and assessing coronary angioplasty; 4) described the morphometric features of atherosclrotic plaques, analyzed by computer cinevideodensitometry which increase the likelihood of coronary occlusion; 5) determine the magnitude of coronary stenotic lesions which cause exercise-induced left ventricular dysfunction, and reduced myocardial blood flow in the right coronary artery at rest. All computer and microprocessor equipment necessary is available in our laboratory, and no capital equipment expenses are requested in this application. The basic goals of the proposed research in this continuation application are unchanged: 1) to provide clinicians with an accurate and rapid method for quantifying the severity and morphology of coronary atherosclerotic lesions in patients preoperatively; and 2) to provide clinicians with objective information about the dimensions of coronary stenotic lesions which reduce regional flow, effect left ventricular function, result after coronary angioplasty, and enhance the likelihood of coronary thrombosis.